Super tiny extract route_typed_request_once (#14951)

sgl-model-gateway/src/routers/http/router.rs

@@ -175,7 +175,42 @@ impl Router {
             &self.retry_config,
             // operation per attempt
             |_: u32| async {
-                let worker = match self.select_worker_for_model(model_id, Some(&text)) {
+                self.route_typed_request_once(headers, typed_req, route, model_id, is_stream, &text)
+                    .await
+            },
+            // should_retry predicate
+            |res, _attempt| is_retryable_status(res.status()),
+            // on_backoff hook
+            |delay, attempt| {
+                RouterMetrics::record_retry(route);
+                RouterMetrics::record_retry_backoff_duration(delay, attempt);
+            },
+            // on_exhausted hook
+            || RouterMetrics::record_retries_exhausted(route),
+        )
+        .await;
+
+        if response.status().is_success() {
+            let duration = start.elapsed();
+            RouterMetrics::record_request(route);
+            RouterMetrics::record_generate_duration(duration);
+        } else if !is_retryable_status(response.status()) {
+            RouterMetrics::record_request_error(route, "non_retryable_error");
+        }
+
+        response
+    }
+
+    async fn route_typed_request_once<T: GenerationRequest + serde::Serialize + Clone>(
+        &self,
+        headers: Option<&HeaderMap>,
+        typed_req: &T,
+        route: &str,
+        model_id: Option<&str>,
+        is_stream: bool,
+        text: &str,
+    ) -> Response {
+        let worker = match self.select_worker_for_model(model_id, Some(text)) {
             Some(w) => w,
             None => {
                 RouterMetrics::record_request_error(route, "no_available_workers");
@@ -239,28 +274,6 @@ impl Router {
             }
         }
 
-                response
-            },
-            // should_retry predicate
-            |res, _attempt| is_retryable_status(res.status()),
-            // on_backoff hook
-            |delay, attempt| {
-                RouterMetrics::record_retry(route);
-                RouterMetrics::record_retry_backoff_duration(delay, attempt);
-            },
-            // on_exhausted hook
-            || RouterMetrics::record_retries_exhausted(route),
-        )
-        .await;
-
-        if response.status().is_success() {
-            let duration = start.elapsed();
-            RouterMetrics::record_request(route);
-            RouterMetrics::record_generate_duration(duration);
-        } else if !is_retryable_status(response.status()) {
-            RouterMetrics::record_request_error(route, "non_retryable_error");
-        }
-
         response
     }